This May Explain Why You Get Sick When You’re Overtired

If you want to skip the misery that comes with fighting a seasonal cold or flu, new research explains why sleep is some of the best preventive medicine.

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We already knew that not getting enough sleep can lead to an increased risk of getting sick, but Nathaniel Watson, a neurologist and sleep specialist at the University of Washington School of Medicine, said this new research helps explain why.

Sleeping poorly can block specific genetic processes in the cells that make up your immune system, which is responsible for fighting off infections and disease, according to the new study.

“Your immune system is not functioning the way it was meant to when you’re sleep deprived,” Watson said.

This study is the first one that Watson and his colleagues are aware of that looks at what happens to the immune system’s DNA when you’re not getting adequate sleep.

“It’s further evidence of how important sleep is to human health and physiology,” Watson said.

Just an hour of lost sleep can cause cellular damage

The researchers followed 11 pairs of identical twins for the study. One twin reported sleeping at least seven hours per night, while the other slept approximately one hour less per night.

Looking at identical twins helped control for the fact that sleep needs vary by person, Watson explained. Genes account for about 50 percent of our sleep needs, meaning identical twins are the best-case scenario for getting a good comparison.

Each study participant wore a movement-tracking sleep monitor for two weeks, which confirmed that one twin in each pair slept, on average, one hour less than the other. (Total sleep time also included any daytime napping.)

The researchers took blood samples at the end of the study, which revealed that the immune system of the twin who slept less was less active than the twin who slept more. Those who slept less were actually making fewer proteins, the molecules that our bodies run on.

“They had an underperforming immune system,” Watson said of the shorter sleepers, “which would put them at higher risk of getting sick.”

To control for other potential factors that could affect sleep need and immune health, the researchers excluded people from the study who had diabetes, depression or other mental health problems and sleep disorders. They also left out shift workers, smokers, drug users and drinkers.

The big takeaway for individuals is that getting good sleep ― quality as well as quantity ― is a really important element of human health, Watson said.

“Add risk of infection to the myriad reasons why sleep deprivation is bad for you,” he said ― a list that already includes such issues as reduced performance during the day, depression, hypertension, cardiovascular disease, diabetes and irritability.

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Sarah DiGiulio is The Huffington Post’s sleep reporter. You can contact her at sarah.digiulio@huffingtonpost.com.